Human Error and Reliability
What the exam tests
Human Error and Reliability tests whether you can classify errors, explain how defences fail and describe error-management and safety-culture responses. Expect distinctions between slips, lapses, mistakes and violations, plus Reason's model and TEM.
Core rules
- Error is an unintended action or intention that fails to achieve its goal; violation is a deliberate deviation from rules or procedures.
- Slips are execution failures with the right intention (wrong switch); lapses are memory failures (omitted item); mistakes are planning or intention failures (wrong QNH reasoning).
- Reason's Swiss cheese: active failures by front-line operators combine with latent conditions (design, training, procedures, organisational pressure) when holes align.
- Error management has three layers: prevention (design, training, SOPs), containment (checklists, cross-check, automation), and recovery (monitoring, go-around).
- TEM frames threats, errors and undesired aircraft states; countermeasures should be visible in briefing and monitoring.
- Just culture separates human error from reckless or intentional harm; reporting improves learning without removing accountability.
- Performance shaping factors include fatigue, stress, workload, interface design, experience and supervision.
Worked example
During pre-flight, a pilot is interrupted by a phone call and later omits the fuel-quantity check. This is a lapse, not a violation: intention was correct, memory failed. The systemic fix is a sterile-cockpit period for critical checks, a challenge-response checklist and a physical do-not-disturb marker. Blaming the pilot would not address the interruption.
Traps
- Labelling every error a violation.
- Treating 'pilot error' as a cause rather than a starting point.
- Assuming more paperwork prevents error.
- Hindsight bias: judging the decision only by its outcome.